Trimming a ground-effect machine

ABSTRACT

Trimming of an air cushion vehicle is obtained by properly delaying the compensation effect derived from a bracing actuator extending between the vehicle frame and a bearing plate movable relatively to the latter to compensate for possible variations in the distance between this bearing plate and the surface along which the vehicle moves.

United States Patent Croix-Marie 1 Oct. 17, 1972 [54] TRIMMING A GROUND-EFFECT 3,013,505 12/1961 Burke ..104/134 MACHINE 3,340,943 9/1967 Hirsch ..180/1 18 3 332 361 7/1967 Bertin ..104/134 72 Inventor. Francis ean Cro -M V1r I 1 Chafinongmnce y 7 3,559,759 2/1971 Hart ..104/23 FS 3,253,667 5/1966 Mackie ..180/124 [731 Asslgnw 3mm Plals", France 3,318,406 5/1967 Scheel ..180/118 22 Filed; Oct 2, 1970 3,540,378 11/1970 Giraud ..l04/23 FS [21'] App! 77598 Primary Examiner-Gerald M. Forlenza Assistant Examiner-D. W. Keen [30] Foreign Application Priority Data Attorney-Brufsky, Staas, Breiner and Halsey .2, 1 F ..6933700 Oct 969 rance ABSTRACT U-S. Cl.

of an air cushion vehicle is obtained Clt 1 t 1 1 t 1 e" "B611, the compensation effect derived [58] Fleld of Search 104/23 PSI 134; 180/18 from a bracing actuatorextending between the vehicle 80/25 frame and a bearing plate movable relatively to the latter to compensate for possible variations in the [56] References and distance between this bearing plate and the surface UNITED STATES PATENTS along which the vehicle moves.

3,121,401 2/1964 Fields ..104/134 6 Claims, 8 Drawing Figures PATENTED GET 1 7 I972 SHEET 2 OF 4 mm W TRIMMING A GROUND-EFFECT MACHINE This invention relates to a corrector or rather a trimming facility for an air cushion vehicle .(ACV) or like ground-effect machine moving along a surface with the interposition of pressure fluid cushions, the invention serving to maintain a substantially constant spatial relationship between the vehicle frame and such surface notwithstanding, e.g., an uneven and possibly varying distribution of vehicle loading.

According to this invention trim stabilization is provided automatically by the manner in which the pressure fluid cushion facility is mounted on the vehicle.

According to this invention, the cushion facility is secured to a bearing plate movable relatively to the vehicle frame and connected thereto by mechanical variable-spacer means adapted to move the bearing plate relatively to the frame to compensate for possible variations in the distance between the bearing plate and the surface, the variable-spacer means being associated with means for delaying the compensation provided by the variable-spacer means.

Referring to FIG. 1 of the accompanying drawing, if H denotes the distance between the vehicle frame and the bearing surface, h denotes the spacing between the bearing plate and the vehicle frame and h denotes the spacing between the bearing plate and the bearing surface, the invention as just defined can be expressed algebraically as follows: H h h constant in steadystate conditions i.e., when the bearing plate has reached an equilibrium position.

Advantageously, the bearing plate can make universal movements relatively to the vehicle frame i.e., it can shift and rotate and the variable-spacer means are sufficiently flexible or deformable to permit the universal movements. The mechanical variable-spacer means can be a pneumatic jack operating under the control of a detector of the distance H or of any other value dependent thereon, such as the cushion pressure.

In a preferred embodiment of this invention, a member providing a resilient connection between the bearing plate and the vehicle frame is associated with the jack, which applies to the bearing plate a force such that the resultant force arising therefrom and from the force applied to the bearing plate by the cushion is directed so as to increase the spacing h between the bearing plate and the vehicle frame, the resultant force being balanced by a return force produced by the resilient member. Preferably, the pneumatic jack is a deformable chamber to which the cushion pressure is transmitted.

According to a feature of the invention, the cushion is at least partly bounded by at least one solid andpossibly flexible wall or skirt or the like terminating in a free edge near the vehicle bearing surface, the free edge preferably being movable relatively to the bearing plate, the chamber is bounded by two opposite end member, one of which forms part of the vehicle frame and the other of which forme part of the bearing plate, and the bearing plate area to which the pressure of the fluid in the chamber is applied is larger than the projection on the bearing plate of the area bounded by the free edge. The chamber is also bounded laterally by a continuous flexible diaphragm, such as bellows, extending between the vehicle frame and the bearing plate and providing sealing-tightness.

The following description, taken together with the accompanying exemplary non-limitative drawings, will show clearly how the invention can be carried into effeet. In the drawings:

' FIG. 1 is a diagrammatic view in partial section of an ACV co-operating with a fluidified track-and having a system according to this invention;

FIG. 2 is a view in section on the line Il-ll of FIG. 1;

FIG. 3 is a view similar to FIG. 2 but of a different outline;

FIG. 4 is a view similar to FIG. 1 showing a constructional variant of a constructional detail of the system;

FIG.- 5 and 6 are views in section showing the operation of the trim stabilizer;

FIG. 7 is a diagrammatic view in side elevation of an ACV running on an inverted-T-section track and shows how the invention can be used to trim vehicle pitch,

and

FIG. 8 is a view in section of a machine of the kind shown in FIG. 7 to show how the invention can be used for roll trim.

The examples shown in FIGS. 1-6 refer to the case of an ACV co-operating with a fluidified or active track 1 which outputs the pressure fluid required for cushion formation'through a large number of nozzles 2 having individual valves 3 and being opened by means (not shown) near the cushion to be energized when the vehicle passes by, the fluid going through line 4 to nozzles 2. There is no need to give further details of a known track of this kind; a similar system is disclosed in the U.S. Pat. No. 3,540,378 to Giraud.

FIGS. 7 and 8 refer to an ACV borne and guided by an inverted-T-section track or way or the like 5, the vehicle co-operating with the way 5 through the agency of bearing and guiding cushions energized with pressure fluid independently, for instance, from sources 6.

This invention relates more particularly to the actual cushion facility and not particularly to cushion energization and track outline.

In vthe drawings, the system according to this invention is mounted on a frame part 7 of an ACV.

I In the embodiment shown in FIG. 1, the system according to the invention comprises a bearing plate 8 disposed opposite frame 7 which can be the vehicle platform and co-operating with frame 7 to bound a chamber 9 which is sealed laterally by a flexible diaphragm 10, for instance, of canvas, secured at its periphery at places ll, 12 to frame 7 and plate 8 respectively. The latter is also secured to frame 7 by a central cable 13 which has one end 14 secured to frame 7 and which extends freely through aperture 15 in plate 8; at its opposite end the cable 13 has an abutment 16 which keeps a helical spring 17 compressed between abutment l6 and plate 8.

Secured to plate 8 is at least one flexible wall 18 which serves to bound a cushion 19 laterally and which flares outwardly towards its free edge 20 near surface 1. Cushion l9 communicates with chamber 9 through apertures 21 in plate 8 and possibly too through the aperture 15 for cable 13.

Chamber 9 and cushion 19 can be in shape substantially polygonal, for instance, rectangular, as shown in FIG. 2, the diaphragm l0 and the wall 18 each being formed by four elements substantially perpendicular to one another. Advantageously in this case, flexible sealing means are provided at the corners where the elements meet, for instance, in the form of bellows 22 for diaphragm and of sliding straddlers 23 for wall 18.

Alternatively, the general shape used can be a shape of revolution as shown in FIG. 3, in which case diaphragm 10 and wall 18 are continuous and no seal is required.

Also, bellows 10a which can be seen in FIG. 4 and which, with advantage, have substantially zero selfstiffness can be used instead of the semicylindrical or semitoroidal section plain diaphragm 10.

In the cushion system just described, the following dimensional conditions must be observed for the purposes of this invention (see FIG. 1):

The area S on which the pressure P in chamber 9 acts to apply to plate 8 a force tending to increase the spacing h between plate 8 and frame 7 is always greater than the area S which is the sum of that area of plate 8 which is allotted to cushion 19 plus the projection on plate 8 of the wall 18 i.e., the area S is substantially the area on which the pressure P in cushion 19 acts to apply to the plate 8 a force tending to reduce the spacing h between plate 8 and vehicle frame 7. Since the two pressures P and P are normally equal due to the presence of the communicating apertures 21, the effect of the excess AS of the area S over the area S is to create a resultant force P. AS then moves the plate 8 away from the frame 7. This resultant force is opposed by the force of the spring 17, the stressing of which produces an equilibrium position. If the cushion pressure P increases by AP for any reason, the wall 18 bends. outwardly and the distance h decreases (neglecting the very reduced clearance 24, the distance h is also the distance between the plate 8 and the track surface 1). If, however, this overpressure continues for any length of time, it is gradually transmitted to chamber 9 through the apertures 21 and increases the resultant force acting on plate 8, so that the spacing h increases.

If the resilient characteristics of spring 17 are chosen appropriately in dependence upon the deformation characteristics of the means for bounding the cushion 19 i.e., the material of the flexible wall 18 in the particular example described the corresponding variations of h and 11' can readily be devised to compensate for one another over the proposed zone of possible values of AP, so that the distance H between the vehicle frame 7 and the track surface 1 remains substantially constant. In other words:

remains constant despite variations in h and h due to pressure variations lasting long enough for the plate 8 to reach an equilibrium position.

In the event of an abrupt brief pressure variation, for instance, caused by an obstacle or an unevenness on the track, the rate of fluid flow from cushion 19 to chamber 9 through apertures 21 is too small and too brief to equalize the pressures P and P; there is no extension of chamber 9 and the instantaneous local height H decreases. Track or way irregularities are therefore absorbed by the cushion system between the machine structure and the track and do not appreciably react on the vehicle structure.

In short, the effect of the cushion system according to the invention is that an intermediate member namely the bearing plate 8 takes over the control of substantially all motions arising from pressure variations and thus keeps the same virtually completely away from the vehicle frame 7. In other words, trim alterations due to disturbances affect, so to speak, only the plate 8 and do not react to any great extent on the vehicle frame 7. The system according to the invention may therefore properly be called not a suspension nor damping system, although it performs these functions, but above all a trim corrector or stabilizer.

FIGS. 5-8 show clearly the trim stabilization properties of the cushion system according to the invention.

The case shown in FIG. 5 is of a continuous or at least lengthy disturbance illustrated by way of example as an uneven distribution of the load over the frame 7, which is loaded more heavily on the right of FIG. 5' than on the left, as made clear by the masses 25, 26 and the dissymmetrical position of an arrow X denoting the local over loading. As a comparison between the righthand and left-hand cushion facilities will show, the flexible wall 18 of the right-hand facility is bent more than the flexible wall 18 of the left-hand facility but the bearing plate 8 of the right-hand facility is further away from the frame 7 than in the left-hand facility, because the pressure in the cushion 19 and chamber 9 is higher on the right than on the left. h is therefore larger on the right than on the left but h is larger on the left than on the right; whatever happens, the sum H h h remains constant.

Trim stabilization of the vehicle frame 7 despite uneven load distribution illustrated by dissymmetrically located arrow X can be provided lengthwise (see FIG. 7) and transversely (see FIG. 8).

In FIG. 8 there can be seen lift cushion facilities bearing on horizontal surfaces 27 of an inverted T-section track 5 and guide cushion facilities bearing against vertical surfaces28 of track 5. An arrow Y represents a horizontal axis along which a prolonged stress is applied, for instance, due to centrifugal force on a curve or due to a side wind. The stress acts from left to right in FIG. 8 and so causes the flexible guide wall 18' of the guide cushion 19 on the left to bend more than the flexible wall of the guide cushion 19' on the right and, conversely, causes the bearing plate 8' on the left to be further away from the frame 7 than on ,the right, for the chamber 9' is more compressed on the right than on the left. As in the previous case, these variations have substantially no effect on the horizontal distance H between the frame 7 and the respective vertical surfaces 28 of the track 5.

In none of the embodiments is there any continuous fluid flow through chambers 9,9, which are merely connected to the pressure of the cushion 19 or 19 via the apertures 21 or 21'.

As shown in FIG. 4, the apertures 1 can comprise adjustable valves 21a. The valves 21a are opened in the event of a prolonged disturbance, for instance during vehicle loading and unloading.

Also, and as is shown clearly in FIG. 6, the swivel connection 13, 14 enables the bearing plate 8 to tilt relatively to the frame 7 if necessary, more particularly when the vehicle passes over an unevenness inthe surface of the track 1, represented in FIG. 6 by a change of slope at a place 29.

In the examples described with reference to the drawings a cushion 19 is bounded by one or more flexible walls 18 which flare out towards the track surface 1. Other cushion seals surface can of course be interposed between the bearing plate 8 and the vehicle bearing surface 1.

I claim:

1. In a ground effect machine having a rigid frame movable along but at a distance from a surface with the interposition of a pressure fluid cushion formed against said surface within a space confined by cushion-seal means and fed with a permanent supply of pressure fluid, the improvement which includes a system for stabilizing said distance comprising:

a cushion-seal means carrier plate extending intermediate said frame and said surface and movable towards and away relatively thereto, said plate bounding endwise said cushion space opposite to said surface;

a flexible fluidtight wall sealingly fitted between said frame and said movable plate and enclosing therewith a deformable plenum chamber segregated from said permanent supply of pressure fluid to said cushion space; and

flow-resistant passage means between said cushion space and said deformable plenum chamber for transmitting with time-delay to said chamber pressure variations occurring in said cushion space, whereby said movable plate is subjected to the joint but antagonistic effects of instantaneous values of cushion pressure in said space and of delayed values thereof in said chamber respectively exerted on opposite sides of said movable plate.

2. A system as claimed in claim 1, wherein said movable plate side facing said deformable plenum chamber has an eflective area (S) exposed to the pressure therein, and said cushion-seal means define an effective area (S) on said surface which is wetted by said pressure fluid cushion, (S) being substantially larger than (S 3. A system as claimed in claim 2, wherein said cushion-seal means comprises a cushion-skirting arrangement projecting from said movable plate towards said surface and ending with a free edge adjacent said surface, said cushion wetted area (8') being bounded by said free edge.

4. A system as claimed in claim 2, further comprising resilient means urging said movable plate towards said frame, thereby supplementing the action thereon of said cushion pressure in antagonism with that of said plenum chamber pressure.

5. A system as claimed in claim 1, wherein said flowresistant passage means is formed through a portion of UNITED STATES ?ATENT OFFICE 1 QER'HFICATE WF (IORRECTIQN Patent No. 3,698,506 D te October 17, 1972 Inventor(s) Francis Marie Jean CROIX-MARIE It is certified that error appears in the above-identified patent and that said Letters Patent are'hereby corrected as shown below:

In the heading, [72]-Inv entor:, "Francis Jean Grok-Marie" should read Francis Marie Jean Croixflvlarie Column 5, line 4:, after "seals delete surface Signed and sealed this 12th day of. March 197A.

(SEAL) Attest:

EDWARD M.FLETGHE ,JR.. c. MARSHALL DANN' Attesting Officer Commissioner of Patents FORM PO-105O (10-69) USCOMM-DC 60376-P69 a v.5 GOVERNMENT PRINTING omc: I969 o-aoa-su, lb 

1. In a ground effect machine having a rigid frame movable along but at a distance from a surface with the interposition of a pressure fluid cushion formed against said surface within a space confined by cushion-seal means and fed with a permanent supply of pressure fluid, the improvement which includes a system for stabilizing said distance comprising: a cushion-seal means carrier plate extending intermediate said frame and said surface and movable towards and away relatively thereto, said plate bounding endwise said cushion space opposite to said surface; a flexible fluidtight wall sealingly fitted between said frame and said movable plate and enclosing therewith a deformable plenum chamber segregated from said permanent supply of pressure fluid to said cushion space; and flow-resistant passage means between said cushion space and said deformable plenum chamber for transmitting with time-delay to said chamber pressure variations occurring in said cushion space, whereby said movable plate is subjecTed to the joint but antagonistic effects of instantaneous values of cushion pressure in said space and of delayed values thereof in said chamber respectively exerted on opposite sides of said movable plate.
 2. A system as claimed in claim 1, wherein said movable plate side facing said deformable plenum chamber has an effective area (S) exposed to the pressure therein, and said cushion-seal means define an effective area (S'') on said surface which is wetted by said pressure fluid cushion, (S) being substantially larger than (S'').
 3. A system as claimed in claim 2, wherein said cushion-seal means comprises a cushion-skirting arrangement projecting from said movable plate towards said surface and ending with a free edge adjacent said surface, said cushion wetted area (S'') being bounded by said free edge.
 4. A system as claimed in claim 2, further comprising resilient means urging said movable plate towards said frame, thereby supplementing the action thereon of said cushion pressure in antagonism with that of said plenum chamber pressure.
 5. A system as claimed in claim 1, wherein said flow-resistant passage means is formed through a portion of said movable plate which is common to said cushion space and to said plenum chamber, the latter being completely enclosed except for said passage means.
 6. A system as claimed in claim 5, further comprising adjustable valve means on said passage means. 